78 FIELD PARTIES AND OPERATIONS. 
by the movement of the train, and on which were to be made the observations ; and, by detached 
parties, to examine important land-marks and side-routes, and cover as much of the country as 
practicable. Such a general knowledge was thus to be gained of the country as will give the 
means of giving locations of roads, with approximate estimates of cost. 
On reaching Pike lake, on the Red river trail, Lieutenant Grover, in command of a select party 
of nineteen men, was detached to examine a route to Fort Union, by Dead Colt Hillock, whilst 
the main party, under my own personal direction, examined a more northern route, crossing 
the Shayenne river twice, and passing some twenty-five miles south of the Miniwakan lake. 
The trails of the two commands came together in the valley of Mouse river, and they reached 
Fort Union without accident of any kind—Lieutenant Grover on the 25th of July, and the main 
party on the 1st of August. 
It is proper to mention that, in the progress of the main party, much was done in the way of 
reconnaissance by the civil engineer parties. Besides the usual examination on the line, Mr. 
Lander made a reconnaissance of the valley of the Shayenne river, between the two crossings; of 
a portion of the Coteau de Missouri, some twe .ty miles westward of the general route, and of the 
upper valley of Mouse river; and Mr. Tinkham, besides being in charge of the topographical 
survey of the route, added materially to our knowledge of the course and character of the streams 
by detached work. 
Lieutenant Donelson had already preceded the parties operating by land, had made the survey 
of the Missouri to near the mouth of Milk river, and a reconnaissance of the country in the vicinity 
of Fort Union. 
On the 9th of August the command moved from Fort Union in two parties, under the com- 
mand of Lieutenants Donelson and Grover; the former to explore a route leading from the Mouse 
River valley under the 49th parallel, and the latter to take the route of Milk river, travelled by 
the wagons of the Fur Companies, and both to rendezvous at Fort Benton. 
At the Big Muddy river the two commands were united under my own direction, the topo- 
graphical survey of the route placed permanently in charge of Mr. Lambert, and the Milk river 
route pursued by the whole party till it approached within 155 miles of Fort Benton; when, 
leaving the main train in command of Lieutenant Donelson, I went forward with two detached 
parties, under Lieutenant Grover and Mr. Lander, and reached Fort Benton on the 1st of Sep- 
tember. 
Lieutenant Grover was, on the 5th, sent forward to cross the Rocky mountains, and ascertain 
whether Lieutenant Saxton had established a depot at St. Mary’s village, and Mr. Lander was 
ordered to be in readiness to survey the Marias Pass. 
Lieutenant Donelson reached Fort Benton on the 6th of September, and Mr. Tinkham, who by 
my direction had been assigned to the duty of making a general exploration between the Milk 
and Missouri rivers, on the 9th September. 
Dr. Evans, the geologist of the exploration, reached Fort Benton on the 5th September, having 
made a large collection in the Mauvaises Terres, and reconnaissances of the country south of the 
Missouri and Yellowstone, and between the Milk and Missouri rivers. He left Fort Benton for 
Oregon, September 10. : 
Without noticing minor changes of programme, it will be sufficient to state that Lieutenant 
Grover met Lieutenant Saxton near the dividing ridge, and that both reached Fort Benton on 
the 13th September, with information of the establishment of a depot at the St. Mary’s village ; 
that Lieutenant Grover was assigned to the duty of completing the survey of the upper Missouri, 
and of crossing the mountain chains in winter with a dog train, to ascertain the condition of the 
snows ; that a meteorological post was established at Fort Benton, in charge of Mr. Doty and 
three men ; that the wagons were left in store there, and much other public property; that Lieu- 
tenant Saxton went down the Missouri with enlisted men and employés not needed to continue 
the survey, with orders to repair to Washington city ; that the Flatheads were visited at their 
